deps: bump oven/bun from 1.4.0-slim to 1.4.2-slim (#12977)

Bumps oven/bun from 1.4.0-slim to 1.4.2-slim.

---
updated-dependencies:
- dependency-name: oven/bun
  dependency-version: 1.4.2-slim
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Dockerfile.bun

@@ -1,5 +1,5 @@
 # ── Multi-stage Dockerfile for Native Bun Runtime (web-latest-bun) ───────────
-FROM oven/bun:1.4.0-slim AS base
+FROM oven/bun:1.4.2-slim AS base
 WORKDIR /app
 
 RUN apt-get update \
@@ -56,7 +56,7 @@ ENV NODE_ENV=production
 RUN bun run --quiet build
 
 # ── Runner Base stage (100% Bun Native Production Runtime) ──────────────────
-FROM oven/bun:1.4.0-slim AS runner-base
+FROM oven/bun:1.4.2-slim AS runner-base
 
 LABEL org.opencontainers.image.title="omniroute" \
   org.opencontainers.image.description="Unified AI proxy — route any LLM through one endpoint (Bun Native)" \